Free Tool
Zepbound Weight Loss Calculator
This calculator looks up the average weight change published for Zepbound (tirzepatide) in SURMOUNT-1. It reports what happened in a trial. It does not predict what will happen to you.
The published result
In SURMOUNT-1, adults taking Zepbound 10 mg had lost an average of 19.5% of their body weight by week 72. For a starting weight of 233 lb that is about 45 lb. Individual results in the trial varied widely: 88.9% of participants lost at least 5%, and 50.1% lost at least 20%. The placebo group lost an average of 3.1%. Everyone in the trial also received diet and physical activity counselling.
233 lb is the average starting weight of that group in the trial. Enter your own to apply the same average to it. This is the average result of a clinical trial, not a prediction of yours.
The dose is the maintenance dose each group was assigned to. The published result already includes the weeks spent stepping up to it.
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What the trial found, by dose
| Placebo (n=643) | 5 mg once weekly (n=630) | 10 mg once weekly (n=636) | 15 mg once weekly (n=630) | |
|---|---|---|---|---|
| Average starting weight | 104.8 kg | 102.9 kg | 105.8 kg | 105.6 kg |
| Average change at week 72 | −3.1% | −15.0% | −19.5% | −20.9% |
| Lost at least 5% of body weight | 34.5% | 85.1% | 88.9% | 90.9% |
| Lost at least 10% of body weight | 18.8% | 68.5% | 78.1% | 83.5% |
| Lost at least 15% of body weight | 8.8% | 48.0% | 66.6% | 70.6% |
| Lost at least 20% of body weight | 3.1% | 30.0% | 50.1% | 56.7% |
SURMOUNT-1 (ClinicalTrials.gov NCT04184622) enrolled 2,539 adults with obesity (BMI ≥30), or overweight (BMI 27 to <30) with at least one weight-related condition; type 2 diabetes excluded and ran for 72 weeks. It compared Zepbound with placebo. All patients received instruction on a reduced-calorie diet (about 500 kcal/day deficit) and physical activity counselling (minimum 150 min/week). Escalation period of up to 20 weeks followed by the maintenance period; weight reduction assessed after 72 weeks (at least 52 weeks at maintenance dose). How the figures were analysed: Intention-to-treat population (all randomly assigned patients); missing week-72 weights imputed by a hybrid approach (label Table 2, footnote a). Least-squares mean from ANCOVA.
Source: ZEPBOUND (tirzepatide) injection prescribing information, Section 14.1, Table 2. U.S. National Library of Medicine, DailyMed. Label effective August 28, 2026; opened September 18, 2026. Read the prescribing information on DailyMed · SURMOUNT-1 on ClinicalTrials.gov
How this calculator works
It looks up the average percent change in body weight that the Zepbound prescribing information prints for the dose you choose, at the end of SURMOUNT-1, and multiplies your starting weight by it. Nothing else goes into the number: no age, sex, health condition, diet or activity, because the trial does not publish an adjustment a calculator could honestly apply.
Worked example. The 10 mg group lost an average of 19.5% by week 72. For a starting weight of 233 lb: 233 × 19.5 ÷ 100 = about 45 lb.
There is no week-by-week view. The prescribing information prints the result at the end of the trial only, so the calculator shows that result and does not estimate the weeks in between or anything after the trial ended.
Zepbound weight loss calculator questions
How much weight do people lose on Zepbound?
In SURMOUNT-1, the average weight loss at week 72 was 15.0% on 5 mg, 19.5% on 10 mg and 20.9% on 15 mg, against 3.1% on placebo. These are trial averages; individual results varied widely.
Is this a prediction of my weight loss on Zepbound?
No. It is a lookup of the average result published for a clinical trial. It cannot account for your health, your dose changes, your diet or your activity, and individual results in the trial varied widely. Talk to your prescriber about what to expect.
How long did the Zepbound trial last?
SURMOUNT-1 ran for 72 weeks. Escalation period of up to 20 weeks followed by the maintenance period; weight reduction assessed after 72 weeks (at least 52 weeks at maintenance dose). No result past the final week is shown, because the trial ended there.
Who took part in SURMOUNT-1?
SURMOUNT-1 enrolled 2,539 adults with obesity (BMI ≥30), or overweight (BMI 27 to <30) with at least one weight-related condition; type 2 diabetes excluded. All patients received instruction on a reduced-calorie diet (about 500 kcal/day deficit) and physical activity counselling (minimum 150 min/week).
What share of people lost at least 10% of their body weight on Zepbound?
In SURMOUNT-1, among adults assigned to Zepbound 10 mg, 88.9% lost at least 5% of their body weight, 78.1% at least 10%, 66.6% at least 15% and 50.1% at least 20% by week 72.
Where do these numbers come from?
ZEPBOUND (tirzepatide) injection prescribing information, Section 14.1, Table 2. U.S. National Library of Medicine, DailyMed (label effective August 28, 2026; SURMOUNT-1, ClinicalTrials.gov NCT04184622). Every figure on this page is copied from that document.
Can this calculator tell me what Zepbound dose to take?
No. It does not recommend, set or adjust a dose. Your dose and how quickly it is increased are decided by your prescriber, following the prescribing information.
By GLP AI / Editorial. The trial figures and result wording on this page were reviewed by Teresa Maze, RDN, on September 18, 2026. The review did not cover anything else on the page.
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. The information provided should not be used for diagnosing or treating a health condition. Always consult your healthcare provider before starting, stopping, or changing any medication or treatment plan. Individual results may vary.